A telescope is a powerful tool used in exploring objects through the universe. They literally let us see the invisible! Telescopes are also a time machine that allows us to look into the past. The word telescope was derived from the roots of the body, which means "distant" and scopo, which means "to see." Thus, a telescope is a tool that allows us to see distant objects such as the Moon, planets, stars and star clusters, nebulae and distant galaxies. 2009 marked the 400th anniversary of the first telescope pointing to the night sky by the famous mathematician, scientist and astronomer Galileo Galileo. Modern telescopes far exceed optical quality than these early instruments. Just as the pupil of our eye becomes larger in the dark to allow more light, the more telescope optics, the fainter the light from distant stars and galaxies looks brighter, which allows us to see further and rotate into space. The second advantage with a large telescope is its ability to resolve smaller and finer details on extended objects, such as the Moon and planets, and to provide a clear separation of nearby binary stars.
Perhaps you are interested in purchasing a new telescope. Basically, there are two types of telescopes to choose from. A refractor uses lenses to collect and bend light in the form of a cone for focusing. Binoculars are just two refractor telescopes mounted side by side. Reflectors use a set of mirrors to collect light, which is brought to focus by a concave curve (inward like a spoon scoop) on the front surface of the primary (largest) mirror. The light penetrates mainly hollow tubes and reaches the main mirror below. When the reflected cone of light (due to the curve) passes upward through the tube, it is intercepted by a smaller flat (flat) diagonal mirror, set at an angle of 45 degrees relative to the light path. 45 + 45 = 90 degrees, so the light is sent out of the tube at right angles, so that the observer can inspect the focused image through the eyepiece (eyepiece). This is a classic Newtonian reflector, named after another famous scientist Isaac Newton, who created his design. The distance between the primary lens (lens or mirror) and the eyepiece where the focal length is achieved is called the focal length. This is determined by how steep or shallow the curve is in the glass. A large curve will focus the light for a short distance, so the telescopic tube will be correspondingly shorter. The failure curve will increase this distance, requiring a longer tube assembly. Many reflectors are called composite telescopes because of their short, short tubes. This cassegrain design uses a steeply curved primary mirror and a convex (curved exterior like a ball) secondary mirror installed near the upper center of the tube. When light is reflected from this convex curved mirror, the steeply converging rays of light diverge (move apart) and then effectively expand the focus further so that the light path continues through the central hole in the primary mirror (like a donut) and focus outside the back of the tube. Many cassegrains use a special glass plate in the front of the tube to “fix” the path of light from the various problems inherent in this design. They can be called Schmidt Cassegrain or Maksutov.
To direct the telescope's optical tube to a specific place in the night sky, installation will be required. There are basically two types of telescopic mounts. The altazimuth installation has two axes at right angles to each other, where one axis allows the telescope to rotate up and down (altitude) and the other axis left and right (azimuth). This is the simpler of the two. The other type is called equatorial setup. It also uses two axes at right angles to each other, but one of them, called the polar axis, is set in accordance with the axis of rotation of the earth. After that, you simply set the declination axis (north-south) and right ascension (east-west) on the polar axis to point to a specific object, and then simply turn west along the polar axis to trace the object in the sky, since it is seems to be moving due to the rotation of the earth. Surrounding circles can be tied to both axes to search for objects using their celestial coordinates (right ascension and declination). If the polar axis has a clock engine, it will automatically direct this tracking at the same speed as the ground. Many commercial telescopes are now equipped with computer-controlled steering systems and a push-button manual paddle, known as “go-to”. This is great for shooting through a telescope, known as astrophotography. If not, manual knobs with a worm and gears are usually used to manually control the tool. In any case, the installation is usually supported on a pedestal or tripod. Some common types of equatorial bindings include German, fork, English yoke and others.
Many accessories are available or required for proper operation of the telescope. A search is either a small refractor telescope with a wide field of view and a crosshair, or a laser device used to accurately determine the main telescope and “find” an object that is intended for viewing. Eyepieces come in different types and sizes. The magnification is calculated by dividing the focal length of the telescope by the focal length of the eyepiece. For example, a telescope with a focal length of 900 mm with an eyepiece with a focal length of 20 mm will give an increase of 45X (900/20 = 45). Another way to say this is 45 units, which means that objects will be displayed 45 times larger in diameter than that of the naked eye. A common misconception is that magnification determines how powerful a telescope is. Since magnification can be adjusted using different focal length eyepieces for any telescope, the true “power” of the telescope is determined by its size (aperture or diameter). Barlow's lens can magnify any given eyepiece, effectively increasing the focal length of the telescope. Usually they double or triple the magnification of the eyepiece used, so in our previous example we now have 90X or 135X with the same eyepiece. Filters are usually screwed to screw eyepieces into drums and have different colors to improve the features of the planetary part. Lunar filters work well to reduce glare and increase contrast on the moon. Sun filters block all harmful rays, allowing you to safely view sunspots. Other filters are used to reduce ambient light, as in urban areas, allowing you to view small extended objects, such as nebulae. A star diagonal prism or mirror changes the position of the eyepiece, creating a right angle to the normal path of the light. This works well with cassegrain refractors or reflectors, especially when viewing objects with large overheads. Dew caps extend the length of the tubes, preventing the formation of dew on the surface of the lenses or corrector plates.
What are the advantages / disadvantages for any type of telescope? Well, if you want your budget to have such a large and powerful telescope, you should think about whether you intend to place it in a car to transport it to a dark sky, or you intend to constantly mount it in the backyard or observatory Once again, the long-focus telescope will have a longer tube, perhaps not allowing it to be easily integrated into the car. The short-focus telescope, sometimes called the richest field telescopes or RFT, is great for viewing wider fields of view in the sky, exciting beautiful views of rich star clusters and several objects relative to each other at the same time. Long focus telescopes are generally excellent for studying small parts on planets and separating nearby binary stars. Compromise is the loss of portability. Refractors have an optical advantage over reflectors in that they do not suffer from diffraction (light scattered or curved around the edge of the barrier) caused by a central obstacle to incoming light by a diagonal or secondary mirror. If the lens is of high optical quality, the refractor will usually outperform the equalized reflector when creating sharply defined images. Refractors are usually manufactured with a large focus, which makes tube length a problem. In addition, refractors are much more expensive reflectors of the same size. Since the size of the lens or mirror of a telescope is a function of its light absorbing ability, the reflector is generally preferred when large sizes are required.
How about some tips for improving your telescope observation? When starting any observation session, always start with the longest eyepiece of the focal length and the widest field of view to more easily illuminate objects in the telescope. Simply align the telescope by aiming at the top of the tube and pointing it in the general direction of the object in the sky. If you have an equatorial installation with installation circles, you can search for the heavenly coordinates of the object and adjust accordingly. Of course, if you have the “Go” function and you have made the alignment 2 or 3 stars, you can simply press the button on the handle. In any case, your next step is to locate the object in the search and align it so that it appears in the center of the crosshair (for example, a sight). If your finder is optically aligned with the main telescope, the object should appear in the field of view of the eyepiece. When observing false objects, try using a method known as averted vision. Instead of looking directly at the object, look a little sideways and see if you notice that the object looks brighter. This is because this part of the eye retina has more cones that are sensitive to light and dark. Get familiar with the night sky using a planetary sphere, commonly referred to as a star. Get to know the brightest stars and seasonal constellations by name. Visit the planetarium show to find out their relative positions in the sky. It takes time, but the universe is a very patient place that does not mind waiting while we take the first steps towards understanding.
